Hello !! > I am trying to solve this simple linear programming prob using > MixedIntegerLinearProgram and it gives an AttributeError: > LinearFunction instance has no attribute '__float__' exception
This is mainly my fault, and the reason is that min/max arguments do not like to get something different from a real value :-) sage: p = MixedIntegerLinearProgram(maximization=True) sage: x = p.new_variable() sage: p.add_constraint(x[0] + x[1] , min=3) sage: p.add_constraint(20*x[0] + 10*x[1] , max=80) sage: p.add_constraint(x[1] - 2*x[0], max = 0) # This line has changed ! sage: p.set_objective(2*x[0]+3*x[1]) sage: p.solve() 16.0 I will immediately send a patch so that it returns an exception otherwise, and update the manual accordingly. There is something else I wrote which may interest you, though : sage: p = MixedIntegerLinearProgram(maximization=True) sage: x = p.new_variable() sage: p.add_constraint(x[0] + x[1] >= 3) # This line has changed ! sage: p.add_constraint(20*x[0] + 10*x[1] <= 80) # This line has changed ! sage: p.add_constraint(x[1] <= 2*x[0]) # This line has changed ! sage: p.set_objective(2*x[0]+3*x[1]) sage: p.solve() 16.0 Note that is it (very, very slightly) slower than the min/max syntax. I do no think it will make any difference until your Linear Programs have several hundreds of constraints, and even then it will only slow (if at all) the construction of the LP, not the actual solving process. I will also try to take the time to rewrite an up-to-date tutorial for LP in Sage... :-) Have fuuuuuuuuun !!! Nathann -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
